Benzyl 5-[(1,2-dihydro-1,2-dioxonaphth-4-yl)oxy]valerate → 5-[(1,2-Dioxo-1,2-dihydronaphth-4-yl)oxy]valeric Acid

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Reaction Steps

Benzyl ester 502 (1.90 g, 5.22 mmol) was hydrogenated at 30 psi with Pd (400 mg) in ethyl acetate (120 mL) for 6 h. The catalyst was removed by filtration through celite, the solvent was evaporated in vacuo and the residue was oxidized with Ag2O (1.45 g, 6.25 mmol) in Et2O by stirring for 10 h. Following filtration and evaporation of the solvent the product was crystallized from benzene to afford 0.53 g of pure material. The mother liquor was purified by flash chromatography (CH2Cl2/MeOH 15:1), the product dissolved in CH2Cl2, extracted with aqueous NaHCO3 solution, acidified to pH 1 with 3% HCl and extracted back with CH2Cl2 to give additional 0.25 g of pure material (total yield 55%), mp 134-136° C.; 1H NMR (CDCl3) 8.12 (d, J=7.0 Hz, 1H), 7.87 (d, J=7.6 Hz, 1H), 7.70 (t, J=7.5 Hz, 1H), 7.59 (t, J=7.4 Hz, 1H), 7.27 (s, 1H), 4.18 (t, J=5.9 Hz, 2H), 2.51 (t, J=7.0 Hz, 2H), 1.75-2.15 (m, 4H).

Provenance & Evidence